The invention relates to a device for operating a drive unit of a motor vehicle and a method for operating a motor vehicle.
In vehicles with internal combustion engines as well as in vehicles having an exclusive or a partial electric drive, strong driver-generated torque jumps can cause vibrations in the drive train, also referred to as load reversals or load impacts, which can be perceived as an uncomfortable driving characteristic. This applies in particular to torque jumps between an operating phase without torque demand, i,e. a coasting mode, and an operational phase with torque demand, i.e., a traction mode.
DE 10 2007 013 253 A1 discloses a generic device for operating a drive unit of a motor vehicle. The device generates setpoints based on driver-generated input parameters, which are used for controlling the drive unit. The drive unit is in the present case an internal combustion engine and an electric machine. The device recognizes operating conditions having a risk of load impacts. The device hereby processes the setpoints so as to attenuate the load impacts.
Such load impact damping is problematic especially for vehicles with a front axle drive and a rear axle drive that is mechanically decoupled from the front axle drive. In such drive system, the front axle drive and the rear axle drive can respond to jumps in the setpoint torque with different dynamics. When the front axle and the rear axle drive respond differently, the load impact damping on the front axle and at the rear axle may not be matched, resulting in an uncomfortable driving sensation.
It is the object of the invention to provide a device and a method for operating a drive unit of a motor vehicle, wherein impact damping which is comfortable for the vehicle occupant is feasible, in particular in vehicles having front axle drive and rear axle drive.